Manufacturing Technology Lab Lab Experiments

Study of Grinding Machines Lab Experiment

Nov 25 2023

Aim:

Study of Grinding Machines

Introduction

Grinding is a process of material removal in the form of small chips by the mechanical action of abrasive particles bonded together in a grinding wheel. It is basically a finishing process employed for producing close dimensional and geometrical accuracies and smooth surface finish. However in same applications, the grinding process is also applied for higher material removal rates and is referred to as abrasive machining. Generally, in other methods of machining, the work piece is shaped by removing chips using cutting tools having designed geometry, with the tool material is harder than the work material. In such types of machining the process has the following limitations.

The difference in the hardness of the tool and of the work is often limited, resulting tool wear and tool failure.
In the process of removing materials by way of chips, a considerable amount of heat is generated which, when it exceeds a specific level, affects the tool hardness. These conditions always limit the applicable cutting speed.

Types of Grinding

Grinding is done on surfaces of almost all conceivable shapes and materials of all kinds.

Grinding may be classified broadly into two groups.

1. Rough or non-precision grinding. 2. Precision grinding.

Rough GrindingSnagging is done where; a considerable amount of metal is removed without regard to the accuracy of the finished surface. Examples of snag grinding are trimming the surface left by sprues and risers on castings, grinding the parting line left on castings, removing flash on forgings, the excess metal on welds, cracks and imperfections on alloy steel billets.

Precision GrindingThis is concerned with producing good surface finish and high degree of accuracy. Grinding in accordance with the type of surface to be ground is classified as

External cylindrical grinding
Internal cylindrical grinding
Surface grinding
Form grinding

Grinding MachinesGrinding machines are broadly classified into cylindrical grinding machines, internal grinding machines, surface grinding machines and tool & cutter grinding machine, depending on the shape of the ground surface and the type of grinding they do.

Cylindrical Grinding MachinesCylindrical grinding machine is performed to remove material, to produce precise geometry, and to obtain the desired surface finish on external surfaces of round work pieces. These surfaces may be cylindrical, tapers, fillets, grooves, shoulders and other formed surfaces of revolution.

Centre type cylindrical grinding machineCentre type grinding machine is used for single and multi-diameter shafts, especially when the concentricity must be held between diameters ground in the separate operations. In these type of machines, the work piece is supported in between the centre for stock removal. Such machines basically consist of a bed, a wheel head (swiveling or non- swiveling type) and a tail stock. The head stock and tail stock are mounted on a swivel table which is moves to and fro in the bed guide ways. Centre type grinding machines may be manually operated, semi- automatic or fully automatic.

Figure: Slotting Machine

Surface GrindersSurface grinding machines are employed to finish plane or flat surfaces. They are also capable of grinding irregular, curved, convex, and concave surfaces. Conventional surface grinders may be divided into two classes: One class has reciprocating tables for work ground along straight lines, while the other covers the machines with rotating work tables for continuous rapid grinding. Surface grinders may also be classified according to whether they have horizontal or vertical grinding wheel spindles. So there may be four different types of surface grinders:

Horizontal spindle reciprocating table.